Serum glycosaminoglycans from rheumatoid arthritis patients do not

175
Rev Biomed 2005; 16:175-179.
Serum glycosaminoglycans from
rheumatoid arthritis patients do
not affect reactive oxygen
species secretion by normal
monocytes.
Brief Communication
Alejandro Bravo-Cuéllar1, César Ramos-Remus2, Armando Carranco-López1, Georgina Flores-Hernández1,
Piedad del C. Gómez-Contreras1, Simone Orbach-Arbouys3.
1
Centro de Investigación Biomédica de Occidente IMSS, CUALTOS Universidad de Guadalajara,
Departamento de Reumatología, Hospital de Especialidades, CMNO, IMSS, Guadalajara, Jalisco, México,
3
Service de Pharmacie, Hôpital Paul Brousse, Villejuif, France.
2
SUMMARY.
Introduction. Several observations suggest that
macrophages play an important role in the
physiopathology of rheumatoid arthritis (RA). One of
the most important features of RA is the serious cartilage
destruction with consequent glycosaminoglycans
(GAG) release. Here we studied whether GAG from
RA patients can induce peripheral blood monocytes
to secrete reactive oxygen species (ROS), thus being
responsible for the inflammatory injury.
Patients and methods. 10 female healthy
postgraduate student volunteers and 10 female patients
with RA were included. GAG were isolated and
purifified according to Merhraban and Volpi methods.
Mononuclear cells from 15 mL of peripheral blood
were obtained and monocytes were identified by
neutral red coloration and phagocytosis and purified
by adherence to plastic. Chemiluminescence (CL)
was measured on a LKB-1250 Bioluminometer at
37°C. The cuvettes contained 5 x 105 monocytes from
healthy donors resuspended in Hank´s solution without
phenol red at 37°C, pH 7.4. Different GAG
concentrations from either normal volunteers (5, 40,
80, and 160 µg/mL) or RA patients (5 and 80 µg/mL)
were resuspended in Hank´s solution in a standard
volume of 100 µL. To elicit CL emission 100 µL of a
solution containing 4 mg/mL of opsonized zymosan
were added and photoemission was measured every
ten minutes during 60 minutes.
Results. The electrophoretic patterns of serum GAG
obtained from normal volunteers and RA patients were
comparable: in both cases chondroitin 4 sulfate and
chondroitin 6 sulfate were identified. No
chemiluminescent signal was emitted by monocytes in
presence of luminal and GAG, suggesting that GAG
are not able to elicit respiratory burst in those cells,
neither via protein C kinase Ca++ influx nor via Fc
receptors. CL emission by zymosan of peripheral
Corresponding address: Alejandro Bravo-Cuellar, Centro de Investigación Biomédica de Occidente del IMSS. Sierra Mojada 800 Col.
Independencia. CP 44340. Guadalajara, Jal. México.
FAX (52) 36329523
E-mail: [email protected]
Received June 23, 2005; Accepted September 5, 2005.
This paper is also available at http://www.uady.mx/sitios/biomedic/revbiomed/pdf/rb051634.pdf
Vol. 16/No. 3/Julio-Septiembre, 2005
176
A Bravo-Cuéllar, C Ramos-Remus, A Carranco-López, G Flores-Hernández, et al .
monocytes was higher in presence of GAG from RA
patients than that in presence of GAG from normal
volunteers or without GAG (increase of 36%).
However, the difference was not statistically significant.
Conclusion. Serum GAG from patients are not likely
to play a role in the physiopathology of RA linked to
the secretion of ROS by monocytes.
(Rev Biomed 2005; 16:175-179)
Key words: glucosaminoglycan, rheumatoid arthritis
patients, oxygen reactive species, monocytes.
RESUMEN.
Glucosaminoglicanos séricos de pacientes con
artritis reumatoide no afectan la secreción de
especies reactivas de oxigeno de monocitos
normales.
Introducción. Diversas observaciones sugieren que
los macrófagos juegan un papel importante en la
fisiopatología de la artritis reumatoide (AR). Uno de
los más importantes hallazgos de la AR es la importante
destrucción del cartílago con la consecuente liberación
de glucosaminoglicanos (GAG). Nosotros estudiamos
si los GAG de pacientes con AR pueden inducir a los
monocitos de sangre periférica a secretar especies
reactivas de oxígeno (ROS), siendo entonces
responsables de la lesión inflamatoria.
Pacientes y Métodos. Diez mujeres voluntarias
estudiantes de postgrado y 10 pacientes femeninas
con AR fueron incluidas. El GAG fue aislado y
purificado de acuerdo a los métodos de Merhraban y
Volpi. Se obtuvieron células mononucleares de 15 mL
de sangre periférica, los monocitos fueron
identificados por la coloración de rojo neutral y
fagocitosis y purificados por adherencia al plástico.
La quimoluminicencia (CL) fue medida en un
Bioluminómetro LKB-1250 a 37ºC. Los recipientes
conteniendo monocitos en una cantidad de 5 x 105 de
los donadores sanos se resuspendieron en una solución
de Hank sin rojo fenol a 37ºC y un pH de 7.4.
Diferentes concentraciones de GAG de voluntarios
normales (5, 40, 80 y 160 µg/mL) o pacientes con
AR (5 y 80 µg/mL) fueron resuspendidos en solución
Revista Biomédica
de Hank en un volumen estandar de 100 µL. Para
obtener la emisión de CL, fueron adicionados 100 µL
de una solución que contenía 4 mg/mL de zymosan
opsonizado y la fotoemisión fue medida cada 10
minutos durante 60 minutos.
Resultados. Los patrones electroforéticos de GAG
obtenidos de voluntarios normales y pacientes con AR
fueron comparables: en ambos casos fueron
identificados condroitin 4 sulfato y condroitin 6 sulfato.
No se emitieron signos de quimoluminicencia por los
monocitos en presencia de luminal y GAG, sugiriendo
que los GAG no son capaces de generar una explosión
respiratoria en esas células ni vía la entrada de Ca++
por protein-quinasa C ni vía los receptores Fc. La
emisión de Cl por zymosan de monocitos periféricos
fue mayor en presencia de GAG en pacientes con
AR, que en presencia de GAG de voluntarios
normales o sin GAG (aumento de 36%). Sin embargo,
la diferencia no fue estadísticamente significativa.
Conclusión. El GAG sérico de pacientes no parece
tener participación en la fisiopatología de la AR a través
de la secreción de ROS por los monocitos.
(Rev Biomed 2005; 16:175-179)
Palabras clave: glucosaminoglicanos, artritis
reumatoide, especies reactivas de oxígeno, monocitos.
INTRODUCTION.
Monocyte-macrophages are cells of the immune
system with important functions which secrete more
than 50 biologically active products including reactive
oxygen species (ROS)(1). Under normal conditions,
monocytes do not attack (self-structures of) the
organism itself. However, cellular alterations can
activate these cells and generate a full response against
itself increasing tissue injury (2). Several observations
strongly suggest that macrophages play an important
role in the physiopathology of rheumatoid arthritis
(RA). Affected joints are infiltrated by macrophages
and several monocyte products are found in the
synovial fluid (3). One of the most important features
of RA is the serious cartilage destruction with
consequent glycosaminoglycans (GAG) release (4).
177
Patient glucosaminoglycans not active on monocytes
Some GAG have been reported to enhance ROS
secretion of macrophages and to stimulate Blymphocytes (5) and the glycan part of peptidoglycans
can bind and activate monocytes through CD14
receptor (6, 7). We studied here whether GAG from
RA patients can induce peripheral blood monocytes
to secrete ROS, thus being responsible for the
inflammation.
MATERIAL AND METHODS.
Patients. Written consent was obtained. Two mL of
serum were taken from 10 healthy female postgraduate
student volunteers and from 10 female patients with
RA from the Rheumathology Departament of the
National Medical Center of Occident of the Mexican
Social Security Institute, Guadalajara, Jalisco México,
diagnosed according to the American Rheumatism
Association criteria (8) and not having taken antiinflammatory drugs during 10 days before the assay.
Extraction and purification of serum
glycosaminoglycans (GAG). GAG were isolated
and purifified according to Merhraban and Volpi
methods (9, 10).
Monocyte collection. Mononuclear cells from 15
mL of peripheral blood were obtained from 10 healthy
volunteers and from the patients by centrifugation on
density gradient with ficoll-hypaque, washed 3 times
with Hank´s solution without phenol red at 4°C. As
previously described (11,12) monocytes were
identified by neutral red coloration and phagocytosis
and purified by adherence to plastic. Viability was
determined by trypan blue exclusion (99% were viable
cells).
Chemiluminescence (CL). Samples were measured
on LKB-1250 Bioluminometer at 37°C. The cuvettes
contained 5 x 105 monocytes from healthy donors
resuspended in 780 µL of Hank´s solution without
phenol red at 37°C pH 7.4. Twenty µL of a luminal
suspension were added (5 x 10 -6 M final
concentration). Different GAG concentrations from
either normal volunteers (5, 40, 80, and 160 µg/mL)
or RA patients (5 and 80 µg/mL) were resuspended
in Hank´s solution without phenol red in a standard
volume of 100 µL and added to the cuvettes. To elicit
CL emission 100 µL of a solution containing 4 mg/mL
of opsonized zymosan was added and photoemission
was measured every ten minutes for 60 minutes.
Results were expressed in millivolts per minute (mV/
min). Each test was done in triplicate (12).
Statistical analysis. Results represent mean ±
standard deviation of 10 independent observations in
each group. Differences between groups were
calculated with the non-parametric Mann Withney Utest.
RESULTS AND DISCUSSION.
The electrophoretic patterns of serum GAG
obtained from normal volunteers and RA patients were
comparable: in both cases chondroitin 4 sulfate and
chondroitin 6 sulfate were identified.
Since it has been reported that inert particles or
biological molecules can elicit CL emission by
phagocytic cells (1), we first studied if serum GAG
from normal volunteers or from patients could also
induce that secretion. Peripheral monocytes were
incubated with luminal and different GAG
concentrations, either from normal volunteers (5, 40,
80 and 160 µg/mL) or from RA patients (5 and 80 µg/
mL). We measured photoemission during 10 minutes:
no photoemission was observed. 5.5 ± 2.8 mV/min
correspond to CL emission background.
We also tested if the addition of GAG can modify
CL emission of peripheral monocytes elicited by a
phagocytic stimulus (opsonized zymosan). The addition
of GAG from healthy volunteers did not modify the
response (194.7 ± 165 mV/min versus 171 ± 110 to
225 ± 165 mV/min at the tested concentrations) (Table
1). The addition of GAG from RA patients at the
concentration of 5 µg/mL slightly increased the intensity
of the emission without reaching statistical significance
(264 ± 215 mV/min). Higher GAG concentration did
not modify the response (210 ± 145 mV/min).
No chemiluminescent signal was emitted by
monocytes in the presence of luminal and GAG,
suggesting that GAG are not able to elicit respiratory
Vol. 16/No. 3/Julio-Septiembre, 2005
178
A Bravo-Cuéllar, C Ramos-Remus, A Carranco-López, G Flores-Hernández, et al .
Table 1
Effect of serum GAG from either RA patients or healthy volunteers on the zymosan elicited
chemiluminiscence of peripheral monocytes in healthy volunteers.
PROTEOGLYCAN CONCENTRATION
Healthy volunteers
_________________________________________
5
40
80
160
MV/min
194 ± 87 225 ± 165 197.9 ± 115 171 ± 108 171 ± 110
( µg/ mL)
Rheumatoid artritis
_________________
5
80
264 ± 115
210 ± 145
D%
16
1.6
-11.8
-12
36
8
U-Mann
Withney
NS
NS
NS
NS
NS
NS
Peripheral monocytes from normal volunteers were incubated in luminol and different concentrations
of GAG from either in healthy volunteers or rheumatoid artritis patients.
burst in those cells neither via protein C kinase, Ca++
influx nor via Fc receptors, mechanism involved in
the activation of respiratory burst of phagocytic cells
(12).
CL emission by zymosan of peripheral
monocytes was higher in presence of GAG from RA
patients, than that in presence of GAG from normal
volunteers or without GAG (increase of 36%).
However the difference was not statistically
significant. This observation may have resulted from
variability between donors, although the statistical test
used did not take the standard deviation into
consideration. A dose-response curve was not
obtained independently of which type of GAG used.
These results suggest that GAG do not regulate
phagocytic stimulus elicited respiratory burst of
monocytes and do not show scavenger activity which
would be interesting in RA (13).
Since GAG such as hyaluronic acid and heparin
can modify immune response or such as heparin
sulfate, an heterogeneous GAG, can induce cytotoxic
activities in macrophages our results suggest that to
obtain significant modifications in immune cell
reactivity a critical GAG structure that may be altered
by inflammatory process is necessary (5).
In conclusion, serum GAG from patients is not
Revista Biomédica
likely to play a role in the physiopathology of RA linked
to the secretion of ROS by monocytes.
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